Installation
Alarm Connections
10
6502B RF Distribution User Guide
15247-201 Rev. B
– April 2009
Figure 4. Daisy Chaining Multiple Modules
The example in Figure 4 shows three units. The original signal from the source is
connected to the top IN connector on the right side of the first module. The lower IN
connector on the first module is connected to the top IN connector on the second
module. The second module is connected to the third module in the same fashion.
The impedance switch for the first and second chassis is set to HI Z, while the
impedance switch on the third (or last) chassis in the daisy chain is set to 50
Ω
.
Alarm Connections
The Symmetricom 6502B provides for an alarm to signal the failure of any signal
output. One set of form-C relay contacts is provided on the 9-pin D connector
labeled ALARMS. For normal operation, pins 1 to 2 are open and pins 1 to 3 are
closed. The sense is reversed for a fault condition. Refer to Figure 5.
Figure 5. Alarm Contacts
If the input signal or input buffer fails or falls below the factory-set low-level
threshold, the red fault indicator next to the input connector will turn on. Likewise, if
any output buffer fails or falls below the low-level threshold, a red fault indicator next
to that output will turn on. The ALARM form-C relay is normally energized,
indicating no signal failure. If either the input or any output signal fails, the relay is
de-energized (short between pins 1 and 2), indicating a fault condition. This is a
fail-safe design that will indicate a fault in the event of a power loss.
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